Rockwell Automation 1771-CFM,D17716.5.99 CONFIGURABLE FLOWMET - Manual (Page 82)

Replace Your QRD Module D–8
Publication 1771Ć6.5.99 - December 1995
The CFM module, configured for QRD module emulation, operates
as a QRD module. Use the following section for reference on how
the CFM (QRD) module operates.
Edit Your Ladder Logic Program
To initiate communication between the CFM (QRD) module and
your PLC processor, you must enter block transfer instructions into
your ladder logic program. The following program example
illustrates the minimum programming required for this
communication to take place.
EN
BTR
BLOCK TRNSFR READ
RACK
GROUP
SLOT
DATA FILE
00
1
0
N23:21
LENGTH
CONTROL BLOCK
0
N23:50
N23:50
15
DN
ER
The CFM (QRD) module is located in rack 0, I/O group 1, slot 0. There are 9 words of data sent from the CFM (QRD)
module to the PLC processor. This data is stored at N23:21. The BTR control file, starting at n23:50, is 5 words long.
CFM (QRD)
BTR EN BIT
CFM (QRD) BTR
CONTROL FILE
Program Example
N CONTINUOUS
Block transfer instructions use one binary file
in a data table section for module location and
other related data. The block transfer data file
stores data that you want transferred to the
module (when programming a BTW) or from
the module (when programming a BTR).
The address of the block transfer data files are
stored in the block transfer control file.
The programming terminal prompts you to
create a control file when a block transfer
instruction is being programmed.
A different block transfer control file is
required for every module.
N23:55
15
CFM (QRD)
BTW EN BIT
The CFM (QRD) module is located in rack 0, module group 1, slot 0. There is 1 word of data sent from the PLC processor
to the CFM (QRD) module. This data is stored at N23:1. The BTR control file, starting at n23:55, is 5 words long.
EN
BTR
BLOCK TRNSFR WRITE
RACK
GROUP
SLOT
DATA FILE
00
1
0
N23:1
LENGTH
CONTROL BLOCK
0
N23:55
N23:50
15
DN
ER
CFM (QRD)
BTR EN BIT
CFM (QRD) BTW
CONTROL FILE
N CONTINUOUS
N23:55
15
CFM (QRD)
BTW EN BIT
Note that the BTW is switch selectable, and its
length is one word. The block transfer should only
be sent once unless the ladder intelligently sets
and clears the reset bits within the block transfer
data. As an example, the ladder might set the
reset bit at the time of overflow. If the block
transfer is sent continuously and the reset bits
contained within the block transfer data are simply
left set to 1", the transfers will constantly be
resetting the totalizer(s) and/or overflow flags of
the specified channels.
Resume Normal Operation